U.S. electronic chipmaker GlobalFoundries has asked European antitrust regulators to investigate market leader TSMC , accusing the Taiwanese firm of unfair competition, an industry source said on Monday. GlobalFoundries is the closest challenger to Taiwan-based TSMC in the foundry, or contract market for making chips for firms without plants of their own, with slightly smaller rivals being UMC of Taiwan and SMIC of China. With TSMC holding 58 percent of the market in 2016, according to market research firm IC Insights, it is the world's top foundry and is also the third biggest chipmaker by sales behind Samsung Electronics and Intel (INTC.O).